Spark PlugsDear Ole Mechanic;

I was going to change the spark plugs in my 1999 V8 Ford pickup the other day, and when I went to buy new plugs there were three different plugs at three different prices from the same company that fit my truck.  The middle-priced one said that it was “copper” and the high priced one said it was “platinum”.  which one should I use and what is the difference?

Ranch Hand

Dear Ranch Hand;

The answer as to which one you should use is simple.  Your 1999 Ford came with platinum-tipped high-priced spark plugs and that is what should go back in it.  If you are removing the factory installed original plugs, you may notice that on four of them there is a tiny platinum button on the ground electrode and on the other four the button is only on the center electrode.  This was a cost savings for the factory, involving less platinum, because they know which electrode the electronic-controlled ignition will eat away in each spark plug hole.  The new plugs have a tiny button of platinum on both the ground and center electrodes.  These replacement plugs are made that way so that they can be used in any of the plug holes.

Now for the “What is the difference?” part of your question.  The standard or cheapest spark plug would work OK in your Ford for a SHORT while, but if you use them you would need to replace them every 10,000 to 20,000 miles.  They would only last about one-fourth as long as the platinum-tipped ones.  The “copper” plugs are designed to transfer heat better under heavy loads--like when you are towing that full 18-foot livestock trailer.  Consequently, they would last about twice as long as the standard plugs but only about one half as long as the platinum tipped ones.

All of the above statements apply to a truck with an engine in good mechanical condition.  If, on the other hand, the truck has 200,000 plus miles on it, burns a quart of oil every 200 miles, has had a piece of black tape over the Check Engine light for as long as you can remember and you are changing the plugs every 3,000 miles because they get oil fouled and the engine quits running, then the cheapest spark plug that you can buy is all you need.

Herr Professor Nuzanbolts